I purchased an ato for my 240 reef about a month ago, from e-fins, (algae mower) and could not be happier. The sump water level stays perfect all the time. It can be hooked up several different ways. I have a reserve next to my sump, and when the water level drops a little, it activates the pump, and fills the sump. It can be hooked up to a ro system as well. It is good for fresh or saltwater tanks. it has 4 different mode settings, and is very easy to set up. It took me about 10 minutes. It cost about $119. a good price for a great ato.